RFC 1900 (rfc1900) - Page 2 of 4
Renumbering Needs Work
Alternative Format: Original Text Document
RFC 1900 Renumbering Needs Work February 1996
Increasingly, renumbering will be needed for organizations that
require Internet-wide IP connectivity, but do not themselves provide
a sufficient degree of address information aggregation. Unless and
until viable alternatives are developed, extended deployment of
Classless Inter-Domain Routing (CIDR) is vital to keep the Internet
routing system alive and to maintain continuous uninterrupted growth
of the Internet. With current IP technology, this requires such
organizations to use addresses belonging to a single large block of
address space, allocated to their current service provider which acts
as an aggregator for these addresses. To contain the growth of
routing information, whenever such an organization changes to a new
service provider, the organization's addresses will have to change.
Occasionally, service providers themselves may have to change to a
new and larger block of address space. In either of these cases, to
contain the growth of routing information, the organizations
concerned would need to renumber their subnet(s) and host(s). If the
organization does not renumber, then some of the potential
consequences may include (a) limited (less than Internet-wide) IP
connectivity, or (b) extra cost to offset the overhead associated
with the organization's routing information that Internet Service
Providers have to maintain, or both.
Currently, renumbering is usually a costly, tedious and error-prone
process. It normally requires the services of experts in the area
and considerable advance planning. Tools to facilitate renumbering
are few, not widely available, and not widely deployed. While a
variety of ad hoc approaches to renumbering have been developed and
used, the overall situation is far from satisfactory. There is
little or no documentation that describes renumbering procedures.
While renumbering occurs in various parts of the Internet, there is
little or no documented experience sharing.
2. DNS versus IP Addresses
Within the Internet architecture an individual host can be identified
by the IP address(es) assigned to the network interface(s) on that
host. The Domain Name System (DNS) provides a convenient way to
associate legible names with IP addresses. The DNS name space is
independent of the IP address space. DNS names are usually related
to the ownership and function of the hosts, not to the mechanisms of
addressing and routing. A change in DNS name may be a sign of a real
change in function or ownership, whereas a change in IP address is a
purely technical event.
Expressing information in terms of Domain Names allows one to defer
binding between a particular network entity and its IP address until
run time. Domain Names for enterprises, and Fully Qualified Domain
Names (FQDNs, see RFC 1594) for servers and many user systems, are
Carpenter & Rekhter Informational